I wish I were alone in my head right now. There’s a stray thought scratching around somewhere behind my temples that I know isn’t mine. It’s sneaky, and won’t tell me what it is, or where it came from. When I’m busy i barely notice it, but in the quiet of the night, like now, i can feel it sneaking like a rat in the walls.

Where did it come from? I first noticed something about three days ago and chalked it up to a half-hearted advertising jingle. Every time I try to catch it I get close, and it becomes a little bit clearer. You know how that goes don’t you? I can see it in your expression. That phrase or word just on the tip of your tongue that is just that little nearer every time you try to capture it – but just not quite there.

Just like you know the word when someone else says it, I’m living in hope of hearing that jingle, or song, or turn of phrase – whatever it is – again. It sounds like it’s a famous quote – you know, that one about dolphins and a journey – but has a musical lilt to it. You know the one I mean, it was in that film a few years ago. Anyway, it’s taken up residence and keeps knocking.

I haven’t been able to settle to sleep. What if it’s important? It can’t have come from nowhere, and if it isn’t something I’ve heard then it must be something my own brain is trying to tell me. I just wish I knew what. Maybe it is a sign that something is bothering me. My subconscious has picked up something on a pre-verbal level about a situation, but my conscious brain isn’t listening? That might explain why it feels like I’m snatching at smoke.

Or maybe I’ve misheard something and accepted it at the time, but my brain is trying to work out what the correct phrase is – like someone talking about the Durex Dog instead of the Dulux Dog. At least, I hope there isn’t such a thing as the Durex Dog, but that’s a horror for another time if it is.

You’re trying to think what the phrase is too, aren’t you? It’s something like ‘soloing the leash?’ and the image of a dolphin’s smile. I’ve never trusted dolphins. Anything or anyone that smiles that much is up to something.

So, there’s a thought swimming round and I just can’t work it out. I can’t sleep. What if it’s a memetic attack? Some rogue piece of semiotic programming that’s escaped and has a life of its own, infecting people. A form of words so powerful they travel and live through us? Is that all we are now? Vessels for thoughts and phrases that aren’t even our own but that jump between us without our even knowing it – like: so long, and thanks for all the fish, and on to the next person before they’re even aware of it.

If you can work it out, I’m not even sure I want you to tell me. You’d surely be reinforcing it in both of us. I can see you feeling teased by it too, that’s why I felt I could tell you, but if it is a thought that travels separately from us, then we can’t tell anyone, can we? Wouldn’t that make us an infection vector? Or is it too late?